Various approaches to making a chairs seat and back form fitting for various users are known in the industries of seating manufacture. These approaches range from the rather traditional use of contouring synthetic foam, to seat/back shells that have a degree of flex. There have also been approaches, which employ various mechanisms to vary the firmness of selected areas of a seating structure. Several problems exist with each of these approaches, though.
In the case of simply using foam padding, under normal manufacturing conditions it is difficult if not impossible to properly select contours that fit all of the population. And so often a softer variety of foam must be selected so that the occupants can reform to a degree the contours. And so, either improper contouring must be used or the chair is unsupportive through it being too soft.
In the case of incorporating flex into the shells of a chair, no geometry to date has achieved the proper amount of flex in the right areas to give correct ergonomic comfort for a wide range of individuals. In the case of a sling approach, the curves imparted on the sling by the frame are simple in nature (non-compound) and thus cannot provide the proper contouring necessary for ergonomic comfort. Also, this approach leads to “hammocking”. Hammocking is when the sling is pressed in one area; the areas immediately adjacent have the tendency of folding inward, squeezing the occupant, again not yielding the proper ergonomic curvatures. An additional problem with sling chairs is that if the manufacturer makes the supporting sling surface taut enough to properly support a large-heavy person, the tension on the sling will be too great for a smaller person, resulting in discomfort.
Finally, the present state of the art dictates that the contours a designer may choose in seating design be generic in nature to accommodate the widest range of the population possible. In an effort to increase comfort, manufacturers have produced “sized” (i.e. small, medium and large) chairs that effectively narrow the amount of contouring-compromise that the designer must normally exercise. Unfortunately, this leads to the manufacturer having to tool three independent products instead of one, and the manufacturers, wholesalers, and retailers having to stock (in this example) three times the quantity of product. Additionally, the end user is stuck with a chair that at some point in the future may be the wrong size. Moreover, sizing is not an absolute in defining the particular contours that an individual may desire. This invention addresses these shortcomings with a new and novel approach to seating adjustment and control.